1. Field of the Invention
This invention relates generally to the field of carbon reinforced metal matrix composition and specifically to fiber coatings that enhance wettability without the degradation thereof when exposed to molten metal.
2. Prior Art
Processes for manufacturing carbon or graphite-fiber-reinforced metal matrix composites which have relatively high strength-to-weight and stiffness-to-weight ratios have traditionally had the problem of carbon or graphite fiber resistance to wetting when immersed in molten baths of the metal matrix material and/or degradation of the fibers during the course of said wetting. What has been required then is a process whereby the fibers could be coated with a meterial that not only facilitates wetting, but also protects the fibers against chemical degradation during such processing. One of the prior art processes that has been used is chemical vapor deposition of a thin film of titanium (Ti)-boron (B) on the fiber to facilitate the wetting and alloying of (Ti-B) to the matrix metal to reduce migration of the coating as described in U.S. Pat. No. 3,860,443 of Jan. 14, 1975 to Lachman et al., U.S. Pat. No. 4,082,864 of Apr. 4, 1978 to Kendall et al, and U.S. Pat. No. 4,223,075 of Sept. 16, 1980 to Harrigan, et al. Such deposition, although a meritorious improvement over other prior art methods, is still relatively expensive and not always consistent as to results. Accordingly, there was a need for a process that would enhance the wettability of graphite/carbon fiber while disallowing degradation during the immersion in the molten bath of the metal matrix material.